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1.
To examine the distribution of visual and oculomotor activity across the macaque brain, we performed functional magnetic resonance imaging (fMRI) on awake, behaving monkeys trained to perform visually guided saccades. Two subjects alternated between periods of making saccades and central fixations while blood oxygen level dependent (BOLD) images were collected [3 T, (1.5 mm)3 spatial resolution]. BOLD activations from each of four cerebral hemispheres were projected onto the subjects' cortical surfaces and aligned to a surface-based atlas for comparison across hemispheres and subjects. This surface-based analysis revealed patterns of visuo-oculomotor activity across much of the cerebral cortex, including activations in the posterior parietal cortex, superior temporal cortex and frontal lobe. For each cortical domain, we show the anatomical position and extent of visuo-oculomotor activity, including evidence that the dorsolateral frontal activation, which includes the frontal eye field (on the anterior bank of the arcuate sulcus), extends anteriorly into posterior principal sulcus (area 46) and posteriorly into part of dorsal premotor cortex (area 6). Our results also suggest that subcortical BOLD activity in the pulvinar thalamus may be lateralized during voluntary eye movements. These findings provide new neuroanatomical information as to the complex neural substrates that underlie even simple goal-directed behaviors.  相似文献   

2.
Objective: This study examined motor impairments over 1 year following mild closed head injury (CHI). It is the first study to serially assess long-term oculomotor and upper-limb visuomotor function following mild head trauma.

Methods: Thirty-seven patients with mild CHI and 37 matched controls were compared at 1 week, 3 months and 6 months and 31 available pairs at 12 months post-injury on measures of saccades, oculomotor smooth pursuit, upper-limb visuomotor function and neuropsychological performance. Symptomatic recovery was sampled using the Rivermead Postconcussion Symptoms Questionnaire.

Results: At 1 week, the group with CHI reported high levels of post-concussional symptoms and exhibited prolonged saccade latencies, increased directional errors, decreased saccade accuracy and impaired fast sinusoidal smooth pursuit concomitant with increased arm movement reaction time, decreased arm movement speed and decreased motor accuracy on upper-limb visuomotor tracking tasks. Neuropsychological testing identified deficits only in verbal learning and speed of processing while attention, short-term/working memory and general cognitive performance were preserved. At 3 and 6 months, the group with CHI continued to show deficits on several oculomotor and upper-limb visuomotor measures in combination with some deficits on verbal learning and improved, yet abnormal, levels of post-concussional symptoms. At 12 months, the group with CHI had no cognitive impairment but residual deficits in eye and arm motor function and continued to show elevated levels of post-concussional symptoms.

Conclusions: The findings indicate that multiple motor systems are measurably impaired up to 12 months following mild CHI and that instrumented motor assessment may provide sensitive and objective markers of cerebral dysfunction during recovery from mild head trauma independent of neuropsychological assessment and patient self-report.  相似文献   

3.
Canceling planned action: an FMRI study of countermanding saccades   总被引:5,自引:0,他引:5  
We investigated the voluntary control of motor behavior by studying the process of deciding whether or not to execute a movement. We imaged the human dorsal cortex while subjects performed a countermanding task that allowed us to manipulate the probability that subjects would be able to cancel a planned saccade in response to an imperative stop signal. We modeled the behavioral data as a race between gaze-shifting mechanisms and gaze-holding mechanisms towards a finish line where a saccade is generated or canceled, and estimated that saccade cancelation took approximately 160 ms. The frontal eye fields showed greater activation on stop signal trials regardless of successful cancelation, suggesting coactivation of saccade and fixation mechanisms. The supplementary eye fields, however, distinguished between successful and unsuccessful cancelation, suggesting a role in monitoring performance. These oculomotor regions play distinct roles in the decision processes mediating saccadic choice.  相似文献   

4.
Dense-array electrocortical and functional hemodynamic measures of human brain activity were collected to assess the relationship between 2 established neural measures of emotional reactivity. Recorded in parallel sessions, the slow-wave late positive potential (LPP) and visual cortical blood oxygen level-dependent (BOLD) signals were both modulated by the rated intensity of picture arousal. The amplitude of the LPP correlated significantly with BOLD intensity in lateral occipital, inferotemporal, and parietal visual areas across picture contents. Estimated strength of modeled regional sources did not correlate significantly with regional BOLD intensity. These data suggest that the enhanced positive slow wave seen over posterior sites during emotional picture processing represents activity in a circuit of visual cortical structures, reflecting a perceptual sensitivity to the motivational relevance of visual scenes.  相似文献   

5.
The ability to anticipate predictable stimuli allows faster responses. The predictive saccade (PRED) task has been shown to quickly induce such anticipatory behavior in humans. In a PRED task subjects track a visual target jumping back and forth between fixed positions at a fixed time interval. During this task, saccade latencies drop from approximately 200 ms to <80 ms as subjects anticipate target appearance. This change in saccade latency indicates that subjects' behavior shifts from being sensory driven to being memory driven. We conducted functional magnetic resonance imaging studies with 10 healthy adults performing the PRED task using a standard block design. We compared the PRED task with a visually guided saccade (VGS) task using unpredictable targets matched for number, direction and amplitude of required saccades. Our results show greater activation during the PRED task in the prefrontal, pre-supplementary motor and anterior cingulate cortices, hippocampus, mediodorsal thalamus, striatum and cerebellum. The VGS task elicited greater activation in the cortical eye fields and occipital cortex. These results demonstrate the important dissociation between sensory and predictive neural control of similar saccadic eye movements. Anticipatory behavior induced by the PRED task required less sensory-related processing activity and was subserved by a distributed cortico-subcortical memory system including prefronto-striatal circuitry.  相似文献   

6.
Recent positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) studies in humans have localized the frontal eye field (FEF) to the precentral sulcus (PCS). In macaque monkeys, low-threshold microstimulation and single unit recording studies have located a saccadic subregion of FEF in a restricted area along the anterior wall of the arcuate sulcus and a pursuit subregion located deeper in the sulcus close to the fundus. The functional organization and anatomical location of these two FEF subregions are still to be defined in humans. In the present study, we used fMRI with high spatial resolution image acquisition at 3.0 Tesla to map the saccade- and pursuit-related areas of FEF within the two walls of the PCS in 11 subjects. We localized the saccade-related area to the upper portion of the anterior wall of the precentral sulcus and the pursuit-related area to a deeper region along the anterior wall, extending in some subjects to the fundus or deep posterior wall. These findings localize distinct pursuit and saccadic subregions of FEF in humans and demonstrate a high degree of homology in the organization of these FEF subregions in the human and the macaque monkey.  相似文献   

7.
Passive viewing of biological motion engages extensive regions of the posterior temporal-occipital cortex in humans, particularly within and nearby the superior temporal sulcus (STS). Relatively little is known about the functional specificity of this area. Some recent studies have emphasized the perceived intentionality of the motion as a potential organizing principle, while others have suggested the existence of a somatotopy based upon the limb perceived in motion. Here we conducted an event-related functional magnetic resonance imaging experiment to compare activity elicited by movement of the eyes, mouth or hand. Each motion evoked robust activation in the right posterior temporal-occipital cortex. While there was substantial overlap of the activation maps in this region, the spatial distribution of hemodynamic response amplitudes differentiated the movements. Mouth movements elicited activity along the mid-posterior STS while eye movements elicited activity in more superior and posterior portions of the right posterior STS region. Hand movements activated more inferior and posterior portions of the STS region within the posterior continuing branch of the STS. Hand-evoked activity also extended into the inferior temporal, middle occipital and lingual gyri. This topography may, in part, reflect the role of particular body motions in different functional activities.  相似文献   

8.
Prediction error--a mismatch between expected and actual outcome--is critical to associative accounts of inferential learning. However, it has proven difficult to explore the effects of prediction error using functional magnetic resonance imaging (fMRI) while excluding the confounding effects of stimulus novelty and incorrect responses. In this event-related fMRI study we used a three-stage experiment generating preventative- and super-learning conditions. In both cases, it was possible to generate prediction error within a causal associative learning experiment while subtracting the effects of novelty and error. We show that right lateral prefrontal cortex (PFC) activation is sensitive to the magnitude of prediction error. Furthermore, super-learning activation in this region of PFC correlates, across subjects, with the amount learned. We thus provide direct evidence for a brain correlate of the surprise-dependent mechanisms proposed by associative accounts of causal learning. We show that activity in right lateral PFC is sensitive to the magnitude, though not the direction, of the prediction error. Furthermore, its activity is not directly explicable in terms of novelty or response errors and appears directly related to the learning that arises out of prediction error.  相似文献   

9.
Respiratory disorders after abdominal surgery are commonly explained by changes in diaphragmatic movement that are difficult to demonstrate and quantify. Our aim was thus to quantify these changes using a noninvasive method. We used M-mode sonography for the prospective study to measure diaphragmatic amplitude in 14 patients before and after cholecystectomy. During quiet breathing, the diaphragm inspiratory amplitude (DIA) was significantly decreased after surgery from 1.4 +/- 0.2 cm to 1 +/- 0.1 cm and from 1.6 +/- 0.3 cm to 1.2 +/- 0.3 cm in the Laparoscopic and Open Cholecystectomy groups, respectively. The total time cycle of diaphragmatic motion decreased significantly in the two groups. The DIA also decreased significantly during deep breathing after cholecystectomy from 6.0 +/- 0.8 cm to 3.0 +/- 1.8 cm and from 6.1 +/- 1.3 cm to 3.1 +/- 1.6 cm in the Laparoscopic and Open Cholecystectomy groups, respectively. The six patients who underwent spirometric examination showed, during quiet breathing, a significant decrease in DIA without change in tidal volume, i.e., 0.51 +/- 0.08 L to 0.45 +/- 0.08 L. We found a significant decrease in DIA after cholecystectomy and a significant interindividual correlation between DIA during deep inspiration and inspiratory capacity. Using M-mode sonography techniques, we were able to demonstrate changes in diaphragmatic mobility after laparoscopic or open cholecystectomy. IMPLICATIONS: Cholecystectomy at times results in impaired respiratory and diaphragmatic functions. The techniques currently used to study these repercussions are both laborious and invasive. Our sonographic technique is completely noninvasive and can be used to study diaphragm morphology and movement in real time.  相似文献   

10.
Previous studies have indicated that largely overlapping parts of a complex, mainly fronto-parietal, neural network are activated during both observation and execution of an action. If these two processes are inextricably linked, increases of neural activity contingent upon action observation should be found only for movements that can actually be performed. Using functional magnetic resonance imaging, we investigated whether observation of possible and biomechanically impossible movements of fingers activated the same neural systems. Thirteen healthy subjects were scanned during observation of video-clips showing abduction/adduction movements of the right index or the little finger, which were defined as biomechanically possible or impossible according to the range of their angular displacement at the metacarpo-phalangeal joint. The mere observation of possible and impossible hand movements induced a selective activation of left precentral and left inferior frontal regions, thus indicating that motor-related areas map body actions even when they violate the constraints of human anatomy. An increase of the blood oxygen level-dependent signal selectively linked to observation of impossible hand movements was found in sensorimotor parietal regions. Our results suggest that while premotor areas code human actions regardless of whether they are biologically possible or impossible, sensorimotor parietal regions may be important for coding the plausibility of actions.  相似文献   

11.
We used behavioral and functional magnetic resonance imaging (fMRI) methods to probe the cerebral organization of a simple logical deduction process. Subjects were engaged in a motor trial-and-error learning task, in which they had to infer the identity of an unknown 4-key code. The design of the task allowed subjects to base their inferences not only on the feedback they received but also on the internal deductions that it afforded (autoevaluation). fMRI analysis revealed a large bilateral parietal, prefrontal, cingulate, and striatal network that activated suddenly during search periods and collapsed during ensuing periods of sequence repetition. Fine-grained analyses of the temporal dynamics of this search network indicated that it operates according to near-optimal rules that include 1) computation of the difference between expected and obtained rewards and 2) anticipatory deductions that predate the actual reception of positive reward. In summary, the dynamics of effortful mental deduction can be tracked with fMRI and relate to a distributed network engaging prefrontal cortex and its interconnected cortical and subcortical regions.  相似文献   

12.
Brain functions during the resting state have attracted considerable attention in the past several years. However, little has been known about spontaneous activity in the sensory cortices in the task-free state. This study used functional magnetic resonance imaging (fMRI) to investigate the existence of spontaneous activity in the primary visual areas (PVA) of normal-sighted subjects and to explore the physiological implications of such activity. Our results revealed that we were able to detect spontaneous activity, which was nonrandom in that it was distinctly clustered both temporally and spatially in the PVA of each subject. In addition, the neural network associated with the PVA-related spontaneous activity included the visual association areas, the precuneus, the precentral/postcentral gyrus, the middle frontal gyrus, the fusiform gyrus, the inferior/middle temporal gyrus, and the parahippocampal gyrus. After considering the functions of these regions, we speculated that the PVA-related spontaneous activity may be associated with memory-related mental imagery and/or visual memory consolidation processes. These findings confirm the presence of spontaneous activity in the PVA and related brain areas. This confirmation supports the perspective that brain is a system intrinsically operating on its own, and sensory information interacts with rather than determines the operation of the system.  相似文献   

13.
Ideational apraxia is characterized by impaired knowledge of action concepts and proper object usage. The present functional magnetic resonance imaging study aimed at investigating the neural system underlying conceptual knowledge for proper object use in healthy subjects, when the effects of visuospatial properties and perceptual modality were taken into account. Subjects performed semantic decision tasks requiring retrieval of knowledge about either object functional purposes (functional task) or visuospatial object properties (visuospatial task) and perceptual control tasks. The semantic tasks were performed with pairs of either written object names or object drawings. Activation for the functional task in common for words and pictures, compared with the visuospatial and control tasks, was found in left parietal-temporal-occipital (PTO) junction, inferior frontal, anterior dorsal premotor, and presupplementary motor areas. Ventral inferior frontal cortex activation correlated negatively with reaction time in the functional condition. No specific activation characterized the visuospatial task compared with the functional task. The conceptual tasks, compared with the control tasks, demonstrated overlapping activation in left PTO junction, prefrontal, dorsal premotor, cuneus, and inferior temporal areas. These results outline the neural processes underlying conceptual knowledge for proper object use. The left ventral inferior frontal gyrus might facilitate behavioral decisions regarding functional/pragmatical object properties.  相似文献   

14.
BACKGROUND: Functional magnetic resonance imaging (fMRI) using blood-oxygen-level-dependent (BOLD) contrasts is a common method for studying sensory or cognitive brain functions. The aim of the present study was to assess the effect of the intravenous anaesthetic propofol on auditory-induced brain activation using BOLD contrast fMRI. METHODS: In eight neurosurgical patients, musical stimuli were presented binaurally in a block design. Imaging was performed under five conditions: no propofol (or wakefulness) and propofol plasma target concentrations of 0.5, 1.0, 1.5, and 2.0 microg ml(-1). RESULTS: During wakefulness we found activations in the superior temporal gyrus (STG) corresponding to the primary and secondary auditory cortex as well as in regions of higher functions of auditory information processing. The BOLD response decreased with increasing concentrations of propofol but remained partially preserved in areas of basic auditory processing in the STG during propofol 2.0 microg ml(-1). CONCLUSIONS: Our results suggest a dose-dependent impairment of central processing of auditory information after propofol administration. These results are consistent with electrophysiological findings measuring neuronal activity directly, thus suggesting a dose-dependent impairment of central processing of auditory information after propofol administration. However, propofol did not totally blunt primary cortical responses to acoustic stimulation, indicating that patients may process auditory information under general anaesthesia.  相似文献   

15.
BACKGROUND: Cell implantation into ischemic regions has recently been introduced as a novel strategy for therapeutic angiogenesis. Little is known, however, about the process of blood vessel regeneration, particularly that of the inferior vena cava (IVC). The indicators of normal angiogenesis are also unestablished. PURPOSE: To investigate the process of regeneration of the IVC from a histological viewpoint and to speculate on how the new formation and regeneration of the blood vessels proceed. MATERIALS AND METHODS: Our previous studies showed that a bioabsorbable polymer patch implanted into the IVC formed vessels resembling the native IVC (J Gastrointest Surg 2005;9:789). Using this model system, we investigated the histology and time course of IVC regeneration in the graft site. A 3 x 2 portion of infrahepatic IVC was substituted by a bioabsorbable polymer patch of the same size in hybrid pigs. The patched area was excised for histology at 2 weeks and 3, 6, and 12 months after implantation (n = 3, each). RESULTS: By 2 weeks, the patched area had developed vascular endothelial cells of the same type seen in native veins. The polymer implant was still detectable at 2 weeks but histologically absorbed at 3 months. Smooth muscle was barely formed at 2 weeks, but the ratio of smooth muscle to subendothelial connective tissue gradually increased as time advanced to 3, 6, and 12 months. Even at the last observation at 12 months, however, the amount of smooth muscle formed made up no more than one-half of the native IVC. The case with the elastic fibers accounted for about 90% of the total number of native fibers at 12 months. On gross examination, the patched area resembled the native IVC at 3 months after implantation. CONCLUSION: These results demonstrated that the subendothelial tissue regenerated gradually, requiring more than 1 year to resemble native tissue, whereas the vascular endothelium regenerated in the early phase after injury. Our findings make it possible to establish criteria by which to evaluate venous regeneration.  相似文献   

16.
A hallmark of categorical perception is better discrimination of stimulus tokens from 2 different categories compared with token pairs that are equally dissimilar but drawn from the same category. This effect is well studied in speech perception and represents an important characteristic of how the phonetic form of speech is processed. We investigated the brain mechanisms of categorical perception of stop consonants using functional magnetic resonance imaging and a passive short-interval habituation trial design (Zevin and McCandliss 2005). The paradigm takes advantage of neural adaptation effects to identify specific regions sensitive to an oddball stimulus presented in the context of a repeated item. These effects were compared for changes in stimulus characteristics that result in either a between-category (phonetic and acoustic) or a within-category (acoustic only) stimulus shift. Significantly greater activation for between-category than within-category stimuli was observed in left superior sulcus and middle temporal gyrus as well as in inferior parietal cortex. In contrast, only a subcortical region specifically responded to within-category changes. The data suggest that these habituation effects are due to the unattended detection of a phonetic stimulus feature.  相似文献   

17.
Primary monosymptomatic nocturnal enuresis (PMNE) is a common disorder in school-aged children. However, little is known about resting-state neural function in individuals with PMNE. In this work, resting-state functional magnetic resonance imaging (fMRI) was used to investigate changes in spontaneous brain activity in children with PMNE. We analyzed resting-state fMRI data using statistical parametric mapping (SPM) and a resting-state fMRI data analysis toolkit (REST). Regional homogeneity (ReHo) and amplitude of low-frequency fluctuation (ALFF) values were calculated to analyze spontaneous brain activity in 16 children with PMNE and 16 healthy controls. Children with PMNE exhibited significant differences in ALFF or ReHo in the left inferior frontal gyrus, medial frontal gyrus (Brodmann area, BA 10), and left midbrain. Abnormalities in BA 10 and the inferior frontal gyrus may affect children's decision-making with regard to voiding; abnormalities in the midbrain in PMNE children may influence the internal signal transmission in their bladder control network. Our data indicate that, in children with PMNE, several brain areas related to the micturate control network undergo developmental delay.  相似文献   

18.
BACKGROUND: Chronic pain is common after thoracotomy. The primary goal of this study was to investigate the incidence of chronic post-thoracotomy pain. The secondary goal was to identify possible risk factors associated with the development of chronic post-operative pain. METHODS: We contacted 255 patients who had undergone a classic postero-lateral thoracotomy at our institution in the period between January 2001 and December 2003. All patients received a letter requesting participation; a questionnaire was included with the letter. One week later patients were contacted by telephone to obtain the answers to the questionnaire. RESULTS: We ultimately obtained results from 149 patients (58% of all thoracotomies, 84% of survivors). The overall incidence of chronic post-operative pain was 52% (32% mild, 16% moderate and 3% severe chronic post-operative pain). Patients with chronic post-operative pain reported acute post-operative pain more frequently than those without (85% vs. 62%, P = 0.01), had more severe acute post-operative pain (P = 0.0001), underwent more extensive surgical procedures (P = 0.01), had more constant acute pain (vs. fluctuating pain or pain in attacks) (P = 0.0004) and reported less absence of pain during the first post-operative week (P = 0.0001). There was no significant decrease in chronic pain with time after thoracotomy. CONCLUSION: Our study confirms that chronic post-thoracotomy pain is a common problem. The results from our study suggest that chronic post-thoracotomy pain may be associated with more intensive and extensive nociceptive input due to thoracic surgery.  相似文献   

19.
It has been emphasized that one of the most valuable treatment objectives in dental practice is to afford the patient a pain-free treatment. By the evolution of the laser applications, the dental committee aimed to achieve this goal without analgesic drugs and painful methods. Orthodontic treatment is one of these concerns, that one of the major components of patient to reject this treatment is the pain accompanied during the different treatment phases. Another great concern of the patient is not to get through prolonged periods of treatment. The aim of this study is to evaluate the effect of the low-level (GaAlAs) diode laser (809 nm, 100 mW) on the canine retraction during an orthodontic movement and to assess pain level during this treatment. A group of 15 adult patients with age ranging from 14 to 23 years attended the orthodontic department at Dental School, Damascus University. The treatment plan for these patients included extraction of the upper and lower first premolars because there was not enough space for a complete alignment or presence of biprotrusion. For each patient, this diagnosis was based on a standard orthodontic documentation with photographs, model casts, cephalometric, panorama, and superior premolar periapical radiographies. The orthodontic treatment was initiated 14 days after the premolar extraction with a standard 18 slot edgewise brackets [Rocky Mountain Company (RMO)]. The canine retraction was accomplished by using prefabricated Ricketts springs (RMO), in both upper and lower jaws. The right side of the upper and lower jaw was chosen to be irradiated with the laser, whereas the left side was considered the control without laser irradiation. The laser was applied with 0-, 3-, 7-, and 14-day intervals. The retraction spring was reactivated on day 21 for all sides. The amount of canine retraction was measured at this stage with a digital electronic caliper (Myoto, Japan) and compared each side of the relative jaw (i.e., upper left canine with upper right canine and lower left canine with lower right canine). The pain level was prompted by a patient questionnaire. The velocity of canine movement was significantly greater in the lased group than in the control group. The pain intensity was also at lower level in the lased group than in the control group throughout the retraction period. Our findings suggest that low-level laser therapy can highly accelerate tooth movement during orthodontic treatment and can also effectively reduce pain level.  相似文献   

20.
性行为,癌前疾病与前列腺癌关系的病例对照研究   总被引:7,自引:0,他引:7  
为探讨前列腺癌的危险因素,1991年在中国12个城市实施了以医院为基础的病例对照研究。以138例经组织学确认的前列腺癌现患病例为病例,636例为对照(其中156例医院癌对照,158例医院非癌对照和322例邻居对照),病例与对照以年龄相差不超过5岁和本地居住超过10年为匹配条件。研究结果显示:首次遗精年龄具有超额危险,OR1=1.93.OR2=1.93,OR3=4.2,P<0.05。首次遗精年龄越早,危险性越大,呈明显剂量反应关系。手淫习惯,病例与三种类型对照比较有明显超额危险,OR1=1.8.OR2=1.9,OR3=2.3.P<0.05。婚烟状态,再婚者危险性最高,离异及鳏夫其次,连续婚烟最低。生育孩子数越多越危险,呈现剂量反应关系。前列腺炎及前列腺增生病例与三种类型对照比较,有明确的统计学关联。前列腺炎OR1=4.0,OR2=6.6,OR3=4.9,P值均<0.05。前列腺增生OR1=6.1,OR2=6.6.OR3=4.3.P<0.05。  相似文献   

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